Electrical connections to relatively fine wires in the range of about AWG-30 to AWG-50 have, until relatively recently, been made by winding a portion of the wire around a simple terminal post and then soldering the wire to the post. When the fine wire extends from a coil, the lead wires are similarly soldered to the post.
U.S. Pat. No. 4,026,013 discloses and claims a solderless electrical connection for fine wires comprising an insulating housing having a cavity therein which receives a trapezoidal terminal having obtuse and acute included angles. The electrical connection is established by positioning the wire against one wall of the housing cavity, inserting the terminal and then deforming the terminal in a manner such that it becomes rectangular and one of the sides of the terminal is resiliently pressed into engagement with the wire. The terminal inserting and terminal deforming operations are carried out by a specialized tool having two terminal engaging members, one of which serves to insert the terminal into the cavity and the other one of which deforms the terminal after it has been inserted.
Connecting devices of the type described in the above identified patent are being widely used. However, it is impractical or inconvenient to use this known connection means under many circumstances where connections to fine wires must be made. The terminal shown in U.S. Pat. No. 4,026,013 is of substantial width relative to the diameter of the wire and is impractical for use under many circumstances for this reason. For example, where electrical connections must be made to a winding wire on a small bobbin, the thickness of the terminal and the resulting required dimensions of the terminal housing which must be provided on the bobbin are such that the bobbin cannot be placed in many types of equipment where it is required. The requirement of compound tooling as described above for the terminal shown in U.S. Pat. No. 4,026,013 is also inconvenient under any circumstances where electrical connections must be made to fine wires.
The present invention is directed to the achievement of an improved connecting means for fine wires which requires only an extremely thin flat terminal and a correspondingly relatively thin terminal housing and further, which can be connected to the wire by simply inserting the terminal into the cavity in the housing.
In accordance with a preferred embodiment, the terminal comprises a flat sheet metal member having a leading and a trailing end and fixed spaced-apart fixed links extending between the ends. The fixed links of the terminal serve as the fixed links of two four-bar mechanisms each of which comprises, in addition to a fixed link, two spaced-apart crank links and a floating or connecting link. The connecting links of the two mechanisms extend substantially parallel to each other on each side of a central axis of symmetry and the crank links extend diagonally from the ends of the connecting links to the ends of the fixed links. The arrangement is such that upon positioning a conductor between the connecting links and then applying deforming forces to the ends of the connecting links, the four-bar mechanisms are deformed or deflected until the crank links extend substantially normally, rather than diagonally, of the fixed and connecting links. This deformation of the four-bar mechanisms causes the connecting links to move laterally towards each other so that the conductor is clamped between the opposed edge surfaces of the connected links, thereby to establish contact with the conductor. The housing which receives the terminal has a cavity dimensioned to receive the terminal and a shoulder in this cavity engages the ends of the connecting links during movement of the terminal into the cavity thereby to bring about deformation of the four-bar linkages and the establishment of electrical contact with the wire.